A TWIN-SINGLETON COMPARISON OF PROBLEM BEHAVIOR IN 2-3-YEAR-OLDS

Twin-singleton differences in problem behaviours in 2-3-year-olds were studied. Maternal ratings of children's problem behaviours were obtai ned with the CBCL/2-3. The twin sample consisted of 1363 twin pairs (4 56 MZ, 907 DZ), the sample of singletons consisted of 420 children fro m the general population. Results indicated that the general level of problem behaviours in twins was broadly comparable to that in singleto ns. Four of the seven syndromes showed lower scores for twins. These d ifferences, however, were small and mainly caused by lower scores for DZ twins in comparison to MZ twins and singletons. Part of the differe nce could be attributed to the higher maternal age in the twin groups. Higher means for boys were found for the total problem score, and the Aggressive and Overactive syndromes.